Crowd-sourcing eighteenth-century science: the Great Fireball of 1783

Publishing the Philosophical Transactions has recently been turning its attention to the long Presidency of Sir Joseph Banks and its impact on Phil Trans.  We’ve just begun ploughing through his published and unpublished correspondence held at the Royal Society, and these letters are fantastic; full of scientific information, valuable insight into the processes by which the Transactions were compiled, and bitchy gossip. Among the best are the letters Banks exchanged with Charles Blagden, who kept him apprised of scientific goings-on, opened Banks’s mail for him, and marshalled  the traffic at Banks’s house at 32 Soho Square – a continual back-and-forth flow of books, drawings, journals, newspapers, plant specimens and people – while Banks summered in Lincolnshire.

It was a busy summer for scientific happenings – among other things, the Montgolfier brothers flew the first successful hot-air balloon at Annonay in France, and a craze for ballooning swept Parisian society (Banks did his best to resist the spread of ‘Ballomania’, as it was known, to England – unsuccessfully, in the event – believing it to be a mere fad with no real scientific potential and one that might give considerable scope to unscrupulous entrepreneurs). Henry Cavendish and Joseph Priestley continued their independent experiments on ‘inflammable air’ [hydrogen] and the chemical composition of water (recently recreated for television by Brian Cox in the second instalment of his Science Britannica series, in which he also enthused about the age and significance of Phil Trans).

That same summer a large meteor was seen over England on the night of August 18th, passing rapidly over Scotland and travelling down the east coast of England – it was seen at Lincolnshire, where it appeared to break up but the core continued, still blazing, more or less on its former trajectory , and at Ramsgate.  It was also seen from Brussels and France; and there was an unconfirmed sighting as far south as Rome. Blagden and Banks between them gathered reports of the event from across Britain and the Continent, and Blagden’s paper on the subject based on these observations was published in Phil Trans for 1784 to attempt to estimate the meteor’s size, altitude, and speed; it was visible for a little under a minute, its altitude was estimated variously between 50 and 60 miles, it appeared about as large as the Moon’s disc (Blagden reckoned its diameter at roughly half a mile) and its speed was calculated at 20 miles per second.


‘Meteor seen over Hewit Common near York’, by Nathaniel Pigott (Royal Society L&P/8/92)


These calculations of the meteor’s altitude and speed are remarkably plausible – and if Blagden’s estimate of its size is even marginally accurate then humanity can breathe a two-hundred-year’s delayed sigh of relief at its close shave.  Blagden didn’t see it like that, because he didn’t think meteors were physical bodies but electrical phenomena in the upper atmosphere.  His reasons for thinking this are striking.  When he heard that the Astronomer Royal, Nevill Maskelyne, was sending out queries of his own for an investigation of the comet, he wrote scoffingly to Banks:

‘I hear many years ago Professor [John] Winthrop, of Cambridge [Harvard] in new England, sent a paper to the R.S. containing a circumstantial theory of meteors as bodies revolving in very excentric elipses round our earth, & producing light by their effect upon our atmosphere.  This paper it was not thought proper to print; but most likely [Sir John] Pringle took his ideas from it, which Maskelyne is now going to hash up warm.  If every falling star be such a body, and it seems impossible to draw a line of distinction between them & the larger meteors, we are in high luck indeed that some of them, out of such an immense number, do not now & then miss their way, or get entangled in our atmosphere, and give us a smack.  That this good world may be preserved from such misfortunes is the hearty wish of

Your affectionate


Blagden argued in his published paper that it was precisely because meteors were seen so frequently, yet never felt actually to hit, that they weren’t orbiting bodies like comets.  His crowd-sourced data was remarkably reliable; and from his description of the meteor you would swear he imagined it as a solid body, but he’s forced away from that conclusion because he can’t find any evidence for the logical endpoint of that line of thought: namely, the meteor’s impact.

Blagden’s dismissive mention of John Winthrop, Hollis Professor of natural philosophy and Astronomy at Harvard is intriguing, in this context.  Winthrop’s theory that meteors were of extra-terrestrial origin was substantially correct, and his paper, which the Society hadn’t seen fit to publish at the time, is still in the archives in the Letters & Papers series; but he was also responsible for one of the first attempts to treat earthquakes as geological phenomena.  Like meteors and comets, these had largely been regarded prior to the scientific revolution as manifestations of divine wrath or providential omens; Winthrop’s study of the effects of the devastating Lisbon earthquake of 1755, which had also been felt in New England, attempted to measure the damage it caused and to quantify the forces involved, and he published the resulting lecture in Boston as well as sending an account to the Royal Society. This, along with numerous other descriptions of the Lisbon earthquake, formed the basis of an entire annual volume of Phil Trans.

Crowd-sourcing observations in this way was an important tool in Phil Trans, and continues to be important to modern science; as in the cases of Mass Observation, the Search for Extra-Terrestrial Intelligence (SETI), and numerous other projects.  It’s also crucial to the history of science.  As I write the Royal Society is hosting a wikipedia edit-a-thon on Women in Science, in anticipation of Ada Lovelace Day. Expert volunteers are teaming up to work on the information available in the world’s most consulted encyclopedia, which should give rise to substantial improvements in both the number and quality of entries on women’s contribution to science.